This invention relates to a disc cartridge, and more particularly to a disc cartridge having a disc medium such as a recordable/reproducible optical disc, a magneto-optical disc or the like rotatably received in a casing.
In general, information media including, for example, a disc medium such as a magnetic disc, an optical disc, a magneto-optical disc or the like are each used in the form of a disc cartridge while being received in a casing formed by joining upper and lower casing members to each other. The disc cartridge includes a shutter for selectively opening or closing holes such as head insertion holes, drive shaft insertion holes and the like formed through the upper and lower casing members of the casing. Generally, such a conventional disc cartridge is not provided with any means for taking out the disc medium from the casing for replacement. However, a disc cartridge called a CD caddie which is used for a CD-ROM or the like is constructed so as to permit a CD to be taken out of a casing. Such a CD caddie is adapted to be used in a CD-ROM reproducing unit of the type of using the CD caddie. Thus, the disc medium is used either in the form as taken out from the disc cartridge or in the form as received in the disc cartridge depending on the type of a recording/reproducing unit, thus, it is needed to take out the disc medium from the disc cartridge as required.
However, the conventional disc cartridge including the disc medium takeout mechanism is not constructed so as to permit a shutter mechanism to be arranged on a side of the disc cartridge on which the disc medium takeout cover is pivotally arranged. Also, upper and lower casing members of the casing of the disc cartridge are rendered highly different in configuration from each other. Thus, the disc medium takeout mechanism fails to be applied to a disc cartridge of the vertically reversible type or both-sided type. Another disc medium takeout mechanism has been also proposed which is constructed so as to open only a side surface of the casing opposite from the shutter to take out the disc medium from the disc cartridge. The proposed disc medium takeout mechanism causes the disc medium takeout cover to be operated either detachably or pivotally. Detachable operation of the cover leads to separation or removal of the cover from the casing, resulting in the cover being possibly lost. Pivotal operation of the cover causes the cover to be engaged with the casing through only a pivot shaft, so that the cover, casing or pivot shaft may be broken due to application of a shock or external force to the disc cartridge. Also, it fails to fully close the cover due to inclination thereof, leading to a deterioration in reliability.
In addition, the conventional disc cartridge equipped with the disc medium takeout mechanism is provided with a disc medium takeout cover, which is arranged on the casing of the disc cartridge so as to be pivotally moved for taking out the disc medium from the disc cartridge, so that erasure prevention is carried out only by a lug provided on an opposite side of the casing remote from the cover. Thus, once the lug is removed from the casing, it is required to apply an adhesive tape or the like to a portion of the casing from which the lug was removed, in order to carry out recording on the disc medium again. Unfortunately, this renders handling of the disc cartridge troublesome and causes an adhesive of the adhesive tape and/or the adhesive tape per se to be left on the recording/reproducing unit, to thereby possibly cause a failure or malfunction of the unit.
Whereas, in the conventional disc cartridge which is constructed so as not to permit replacement of the disc medium, an erasure prevention member is arranged so as to be movable between a recordable position and a unrecordable position in the casing, as widely known in the art. Application of such arrangement of the erasure prevention member to the cover-equipped disc cartridge renders takeout of the disc impossible or causes the erasure prevention member to be removed or detached from the casing when the cover is open, because such a disc cartridge is generally constructed so that the erasure prevention member is arranged at a disc takeout section.
Also, the conventional disc cartridge equipped with the disc medium takeout mechanism lacks a detection mechanism for detecting whether the disc medium takeout cover has been opened in order to take out the disc medium from the disc cartridge in the past. When the disc medium is used as taken out from the disc cartridge, there is possibility that a fingerprint, dust or the like is adhered to a surface of the disc medium or the surface thereof is damaged, leading to an error such as wrong recording, a failure in recording or the like during recording operation, resulting in reading-out of data from the disc medium being failed. In order to avoid such a problem, it would be considered to verify a recording section of the disc medium to inspect the disc medium, to thereby check any possible error on the disc medium before the recording operation. However, application of such a system to recording onto the disc medium which has not been taken out from the disc cartridge causes a length of time required for the recording to be double or more, resulting in being impractical.
In view of the problem, a system has been proposed wherein a discrimination section for detecting whether takeout of the disc medium has been carried out in the past is arranged which is constructed so as to vary from an initial state and be never permitted to return to the initial state when the disc medium takeout cover has been opened even once. Thus, the system, so long as the cover has never been open, permits the recording to be accomplished with an increased speed because it is not carried out to verify the disc medium. Also, after the cover has been open, the disc medium is subjected to verification although the verification requires time for the recording, resulting in the recording being substantially free from any error.
Nevertheless, the conventional disc cartridge requires a troublesome procedure that a user operates the discrimination section and then open the disc medium takeout cover. Also, it causes debris produced from the discrimination section of the disc cartridge to enter the casing of the disc cartridge, leading to damage to the disc medium. Further, the debris possibly intrudes into the recording/reproducing unit, leading to a failure or malfunction of the unit, resulting in deteriorating both operability and reliability of the unit.